The arrangement of an interleaved low voltage and high voltage winding wherein the high voltage winding layers are electrically arranged in series and the low voltage winding layers are connected in parallel is disclosed within U.S. Pat. No. 3,895,335. The arrangement of low voltage and high voltage windings are disclosed therein, results in a transformer having a significantly reduced amount of core steel and increased transformer reliability. The winding configuration reduces the radial forces, eddy losses, and stray losses within the transformer. When higher power rated transformers are required however, the division of current between the interleaved low voltage winding layers cannot be completely controlled. Further, the use of this particular winding arrangement with higher power rated transformers is not practical due to the higher current employed and the relatively small number of turns employed within low voltage winding arrangements.
This invention improves over the winding arrangement disclosed within the aforementioned U.S. Patent by providing a plurality of pairs of parallel connected low voltage winding layers wherein the current division between the individual layers can be accurately controlled. The proper division of current within any specific transformer design reduces the transformer reactance and magnetic losses to a minimum value.
The use of series parallel low voltage winding layers is disclosed within U.S. Pat. application Ser. No. 130,412, filed Mar. 14, 1980 (Lamberton). The Lamberton low voltage winding arrangement comprises a "Form S" type high voltage winding wherein all the low voltage winding layers are surrounded by the high voltage winding layers. This is accomplished by first winding the first high voltage winding layer, winding all the low voltage winding layers and then winding the final high voltage winding layer. The Lamberton winding layer configuration differs from that within aforementioned U.S. Pat. No. 3,895,335 in that a series parallel arrangement of low voltage winding layers is located between the inner and outer parts of a high voltage winding.
The instant invention distinguishes over the Lamberton winding arrangement, as well as the arrangement disclosed within the aforementioned U.S. Patent, by providing a "Form S" type high voltage winding, and a "Form S" type low voltage winding with control of current Division in parallel circuits.
A "Form S" type winding is described herein as consisting of an inner and outer part of one winding that surrounds a portion of another winding.